UNCLASSIFIED

AD NUMBER

AD864370

NEW LIMITATION CHANGE

TOApproved for public release, distributionunlimited

FROMDistribution authorized to U.S. Gov't.agencies and their contractors;Administrative/Operational Use; 26 NOV1969. Other requests shall be referred toArmy Missile Command, Redstone Arsenal,AL.

AUTHORITY

USAMC ltr, 1 Dec 1972

THIS PAGE IS UNCLASSIFIED

REPLRT NO. RK-TR-69-I5

FEASIBILITY OF ROCKET MOTORINSULATION INSPECTION USING

INFRARED RADIATION

November 1969

by

D. R. DreitzlerL. B. Thorn

This document is subject to sperial export controlsand each transmittal to foreign governments or foreignnationals may be made only with prior approval of thisCommand, ATTN: AMSMI-RK.

DDC

U094A611Y5W0 6 MVA N"F~ MAN Dr:•

CLEARI NGHOUSE

ror.A AMWMI.I021, I DEC 65 PREVIOUS EDITION IS OBSOLETE

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IWI SECTION4 .. ...........

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071 AVAIL.ad,/r

DISCLAIMERThe findings in this report are not to be construed asan official Department of the Army position unless sodesignated by other authorized documents.

DISPOSMTION INSTRUCT IONSDestroy this report when it is no longer needed.Do not return it to the originator.

I

i,!

I

I

26 November 1969 Report No., RK-TR-69-15

FEASIBILITY OF ROCKET MOTOR I

INSULATION INSPECTION USINGINFRARED RADIATION

by

D. R. DreitzlerL. B. Thorn

1 i

DA Project No. I M262303A205

This document is subject to special export controlsand each transmittal to foreign governments or foreignnationals may be made only with prior approval of thisCommand, ATTN: AMSMI-RK.

1I

Measurements BranchArmy Propulsion Laboratory and Center

Research and Engineering Directorate (Provisional)U. S. Army Missile Command

Redstone Arsenal, Alabama 35809

--------------------- -----

Ii

ii

:- -'÷

ABSTRACT

Insulated, thin-wall motor cases have as a potential failure mode the

burnthrough of the motor case wall resulting from a defective liner. Theobjective of this investigation was to determine the feasibility of the use of - -

infrared radiation as a means of non-destructive examination of an insulated Tmotor case in order to detect a potentially defective liner. A relativelyinexpensive infrared inspection system was designed and assembled which--demonstrated that it is possible to detect cracks and density variations in theinsulation of rocket motor cases.

bI

_64

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ICONTENTS

Page

Section I. INTRODUCTION ............................ 1

Section IiL INSTRUMENTATION DESIGN ........................ 2

1. Scanning Technique ............................ 22. Infrared Detector .............................. 2

Temperature Stabilization 4.........................4

Section III. EXPERIMENTAL RESULTS ......................... 7

1. Detector Temperature Stabilization .... .................. 72. Rotating Disk . ......................... ........ 83. Motor Case Data ............................... 10

Section IV. CONCLUSIONS AND FUTURE PLANS ................. 20

REFERENCES ...................................... 21

ILLUSTRATIONS

Table Page

I Angular Displacement of Recorded Signal Variationsfrom Point 1 .................................. 10

Figure B

1 Detector Scan Path 5..............................5

2 Thermistor Bias Network ........................ 53 Block Diagram of Temperature Controller ................. 64 Wiring Diagram of Temperature Controller .............. 13

5 Controller Step Response ......................... 136 Overall Block Diagram ........................... 147 Disk Scan, Insulated Side Heated .................... 158 Photograph of Insulated Disk ...................... 169 Polar Plot of Detector Response ......................... 17

10 Development of Defective Motor Case .................... 18

11 Successive Scans of Defective Motor Case ................. 19

iiP

• m • n ______ mIlim n m im ~

ABBREVIATIONSK

AD area of detector

A area of sourceS

cm centimeter

C2 cnstat, 1 432cm *

oC degree3 Celsiusd

K degrees Kelvin

6 diameter

dc direct current

e Naperian baseIC7H irradiance

in. inch

IR infrared W

J radiant intensity

mm millimeter

mV millivolt

m W milliwattI IN radiance

n revolutions per second _

NDT non-destructive t 'Lng

NEP noise equivalent power

vP pitch ZR responsivityX

2'

r radius

R compensating thermistor

R ~ sens'-in thermistor

S distance

iv

ABBREVIATIONS (Concluded)

SiN distance from 1 to N

S brightness temperature

t time, variable

r

4 t settling timeT temperatureV voltage I

'~ ~-v velocity

'bb energy of blackbody

alN angle (deg) from 1 to Nemissivitky atX

E enlissivity of source

X wavelength

3141 Ianmicrometer

_

I >3

Tf0 -Gim

M:ý Ah

Section L INTRODUJCTION

Propulsioii system requirements for a maximumi ratio of payload to initialweight has led to the use of thermally insiflated, lightweight, m-otor cases.T11es,;e lightweight cases ~iust WPithstand t~he extremxe temperatures caused by theburning propellant- grain without failure. Evidence of motor case faflure by burn-through indicates a need for an effective non-destructive inspection techniqueadaptabld to prodiction type quality control procedures. This report describesthe feasibility of using IR to m~easure the variations in heat transfer rate throughan unloaded rocket motor case wall and to correlate these measurements wittt

Scracking or unbonding of motor case insulation. This technique was select~be forevaluation since7 it would measure directly the variations in thermal noniductivit~yrather than some other parameter from which the heat transfer rate C-ouid beinferred. Other techniques include ultrasonic [I1 and capacitive 12!.

Sectio-i It. INSTRUMENTATION DESIGN

1. Scannting Techinique

lPapid optical scanning of adhesive-bonded fiat surfaces using111--nethods resulting in detected surface temperature differences of 0. 20C havebeen reported [3]. Optical scanning has the advaitages of: a) A stationarydetector faecilitating the use of sensitive cryogenic detectors. b) high scanning

ý41 ~ speeds re~su1!ing from the use of mirrors; c) an easily in't'rpretable output inthe form of a thermogram, i.e., a thermal pihotograph. The rna~n disadvantagesof optical scanning for tbis application~ are the relatively high cost and the la-,k ofability to e-arnine both s,,es of the surface of a cyindrwthuAovn hcamera or object. it is noted that a complete thermal map of the surface of arocket motor case could be obtained during a static firing if tk~o IR cam oas with3sufficiently short "icanning time were available.

A rocket motor case can be examined for sur.-ace temperature -variationsby mechanical movement of the lB detector, the mnotor case [41, or Loth.M~echanical scanning was deri-ded upon in this case because cf the adaptability ofan. ordinary machinist's lathe. The lathe is used to rotate the empty motor caseat a constant speed while moviing t0e Irt som~or parallel to tile motor axis inearthe case surface. The detector thus covers the exkerljr motor surtare by m~eansof a helical path (Figure 1). The pitch of UPe helix inust be chosen t:) be lessjthan or equal to the diameter, di of a resolution elemnent for complete surfacc

A coverage. The distance, S, traveled by th2 detector on the surface of thecylindAer during one revolution oaaproximtl gvnb

=(7r 2+P meter per revolution).

In most cases P" < (2Tr)- so that S 21rr,

The velocity of dth, motor case -rface with respect to the stationary

2 deecto Isv = 2Trzn (n-ters pe~r second),

wikere n. is in units of revolutions per second. If v ie to be maximized for thedetector recorder ban~1wklth. available, the rotation rate n must be adju-med forthe motor case radius to keep v a constant.

2. Inf~rared Dketetor

Chao•sing a suitable IR deteeior had to include consi,_erat~on for its1&hteded-use (assemnbly lin- NDT of ;notor cases) as well as for the necessary

M -,

-. ~ ~ ~ R --- --- - E---.g.----.------- - -- _ _ _

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technical requirements. For simplicity of operation an uncooled detector wasconsidered essential. Anticipated sourco temperatures at or slightly above3000 K required a wavelength response beyond 9 microns, with a suitable time

constant to facilitate rapid scanning. These restraints, coupled with the avail-ability of a type V-S25-S Barnes thermistor, detector, led to its inrmediateselection. The deiector with integral shielded compensating thermistor wasused in the voltage divider configuration recommended by the manufacturer [5](Figure 2).

The detector was mounted inside a solid block of brass with an aperture• ~~~that limited the field of view to a 60-degree angle. The block was to mairn•.i a j

stable point of operation by providing a heat sink for the detector mount. This

point will be discussed further in the section concerning temperatu stabiliza-tion control of tie detector assembly.

f An approximation of the expected signal voltage was made by assuminga defect that oroduces a temperature differential of 1 ON on the surface of aheated motor case at 35011K with an emissivity c = 0. 5, The radiant power ••= :

differential r.mitted by a defect spot of 0. 75-cun diameter subtendir~g the detectorat a disfance (S) of 0. 050 in. is given by cAs Wbb, where Wbb Wbb( 3 5 1 °K)

- W (350 0K). The irradiance at the detector is calculated frum-~~~ bb - -

cA

H- S•' 2 Wbb

and is equal to approximately 4 x 10-4 watts/cm2.

The signal voltage Vis given by the product of the resporsivity R anud thetotal power- on the detector according to

V = RHAd

By use of the responsivity value of 230 volts per watt specified for the I-mmradetector flake, a signal equal to approximately I mV would be expected. Thit_level was considered sufficiently high when compared to the rated noiseequivalent power of the thermistor which is calculated to be NEP V 4. 2x 10-10 watts. Larger signals will be mea~sured at higher temperatures than351°K.

-3Vf-

3. Temperature Stabilization

The thermistor bolometer is designed to exhibit a maximum rate ofdecrease in resistance with increasing temperature. The thermistor cannot

distinguish random ambient temperature variations from those casued by thedesired signal radiation. The most commonly used technique to decreaseambient temperature sensitivity is shown in Figure 2. It entails the use of acompensating thermistor, R , in series with the sensing thermistor, Rt. Each~.l c-ther;istor flake is designed to be in the same thermal environment except thatA R is shielded from the source radiation to be detected. The output voltage is

then dependent on the signal incident on Rt only, assuming the batteries and

thermistors are identical. This last situation is not exactly realizable, result-ing in. some small dc offset as a result of an ambient temperature change. Thistechnique !does not stabilize the thermal operating point of the thermistor,thereby causing its responsivity to vary with temperature. This effect along

with-the otitput offset problem can be minimized by means of a closed looptemperature control system. The most stable type of controller has beenreported [6] to be of the bridge and amplifier type. It has the ability of provid-ing a-positive or negative voltage output depending on the direction of the errorwith respect to the reference temperature. Use of a Peltier type thermo-el'ctric device results in heat being supplied or removed from the controlleddevice as required. A block diagram of this arrangement is shown in Figure 3.A balancing arrahgement is provided as a part of the bias circuit which is of theWheatstone bridge type. This provides a temperature setting or reference atwhich the circuit will control. The overall gain, i. e., the product of the pre-amplifier and power amplifier gain, is set at the maximum possible value con-sistent with stability considerations. If the gain is excessive the system willhave excessive overshoot or it will oscillate. An approximate gain value ofhalf the unstable value can be used as a first approximation [7].

-4

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Q I- =ln U iinZ

RESOLUTION PITCH

'ROTAT6ION

FEED - V

FIGURE 1. DETECTOR SCAN PATH

300VR

A ~TO RECORDER'

300VR

FIGURE 2. THERMISTOR BIAS NETWORK

5

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BALANCING PE OECIRCUITAMLFEAM IR

IIITEMPERATURE DETECTOR THERMOELECTRIC

FIGURE 3. BLOCK DIAGRAM OF TEMPERATURECONTROLLER

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Section III- EXPERIMENTAL RESULTS oe6b

I. Detector Temperature Stabilization

A wiring diagram of the IR detector temperature controller as usedto obtain the results presented in Section 11m, subsections 2 and 3, is shown inFigure 4. The temperature sensor, Rt, was a 10-kilohm devicewith apower dissips-

tion constant of 1 mW/ °C. Its location in the brass bolometer mounting blockwas selected with respect to overall symmetry. An electrica 4cortnecfdn1bymeans of a shielded cable was made between Rt and the thermistor bias -circuit.

This circuit acts to provide a bias voltage to the thermistor so as to transforima variation in the resistance of Rt resulting from changes in the temperature-of

the brass block to a corresponding voltage. Provision is also made in thebias-circuit for eliminating any dc offset in the voltage output. in effect l deteirmmines the temperature at which the controller will attempt-totifelaintaiitebr:ahssblock. The output voltage of the bias circuit is amplifiedto-provide-sufficientpower to the two thermoelectric devices R and R in series soB4 0to

TEl TE2return the block to its original temperature. Each of the thermoelectric d-eviees-has a heat pumping capacity equivalent to 2 watts at-270C. Anodized-aunuimheat sinks were provided to allow for the heat removal by- natUkral cov-ecti••.-

The stability of the temperature controller was determinedb'yarplyxnga rapid change in temperature to the brass block and observing tbe ,lb o6d:1ooresponse of the system. The procedure used to display the -temperature-stabilltinformation is as follows: -

a) A parallel connection to the preamplifier input shoWn in Figure 4was inade to the Y input of a Mosely 135A X-Y recorder us ed as a-Y-t recorder.

b) The Y input was then calibrated in terms of temperature.

c) R2 was adjusted to provide a zero output at 80 0F.

d) The instrument brass block was then-placed in a Delta MK 2800temperature chamber set at 83oF.

e) The brass block and oven were allowed to reach thermal equilibriuimat a temperature of 76°F.

f) The Delta temperature chambe. and the controller-were thensuimul-taneously energized and the results recorded as shown in FigureS:.The-time domain parameters 18] obtained from Figure 5 are:

7

-7 n n-u

• m-mm mm mm min • mmm o mm lmm m •mmu- --m- m

V,

1) Maximum response 35 mV

2) Final response = 34 mV

3) Rise time, t, = 20 sec

4) 5-percent settling time, t, = 100 sec

5) Percent overshoot = 2.9

6) Period of oscillation = 25 sec.

These figures indicate that the control system is relatively stable.

The reduction in drift (f the thermistor bolometer was determined byrecording the zero drift of the IR detector with the temperature controller onand off. A block diagram of the complete system is shown in Figure 6. With acontroller gain of 2000 the bolometer drift was reduced from 8 to 1 mV/sec.

2. Rotaftin• risk

A number of techniques for appling heat to a test object during IRnon-destructive inspection have been investigated [9]. -'he method selected foruse in this feasibility study is that of scan heating with a localized heat source.This approach was selected in order to minimize overall heating of both thedetector and object being examined.

A disk was selected as the first object to be examined because of the easeof fabrication and simplicity of scanning. The disk was made by attaching a0. 004-inch thick stainless steel disk to a 6. 5-inch diameter plexiglass disk of

0. 25-inch thickness with RTV silicone rubber adhesive. In addition, two0.5-inch holes were drilled in the plastic material equidistant from the diskcenter a distance of 2 inches located on a diameter.

An automobile type lighter element was selected as the IR heat sourcebecause of its small size and high rate of radiant energy transfer. A measure-

X merit of the brightness temperature of the lighter element at the power input of

32 watts (8 volts at 4 amperes dc) used in obtaining the results described in thibsection was made by use of a Leeds and Northrup optical pyrometer. Thepyrometer compared favorably with a Barnes Engineering blackbody at 900 0C.Assuming a value of emissivity of an oxidized nichrome surface (N = 0. 87 for

red light at 0.65 Aim) the true temperature, T, was calculated to be approxi-mately 1180 0K by the Wien equation [10]:

8

7 - -

1 1 X log E{

T S C2 log e

x2The radiating area of the lighter was 1.48 cm2. By use of the Stefan-Boltzmanlaw for the total radiance, the radiant intensity, J = NAs, of the elementbecomes 4.41 watts per steradian.

The disk was rotated by a lathe at approximately 0.4 hertz. The follow-ing three detector source arrangements were evaluated:

a) Source and detector in line on opposite sides of the disk with thestainless steel side heated.

b) Source and detector in line on opposite sides of the disk with heatapplied to the plexiglass side.

c) Source and detector located on the stainless steel side with thesource leading the detector by 90 degrees.

The recorded signal levels corresponding to a), b), and c), respectively,were 1.3, 0. 2, and 0. 7 inches with a recorder sensitivity of 0.5 mV/In. Thesignal recorded by method a) is shown as Figure 7. The indications numbered1 and 4 were visually observed to correspond with the passage of the 0. 5-inch

holes in the plexiglass (Figure 7) past the IR detector. Point 7 is a repeat ofpoint 1. W

The maximum signal variations, numbered 2, 3, 5, and 6, can beattributed to gross density variations in the RTV bonding material. The angulardisplacement of each indication was calculated by means of the relationship:

SIN x 3600 360 =S4.90 N 7 3 .SNdegalN S17

.here

iN = angle from point 1 to N (deg)

S = distance from i to N obtained from Figure 7 (in.)iN

S17 = distance of one complete cycle, obtained as shown above (in.)

The values obtained for the points numbered 1 through 7 are listedinTable I along with the minimum deflection occurring between these points, A

9

-- ~ ~ ~ ~ ~ 4 M ---- t-~ -~

TABLE I. ANGULAR DISPLACEMENT OF RECORDEDSIGNAL VARIATIONS FROM POINT 1

d9Indication 1iN 'iN

__ No. (in.) (deg)M N Maxima Minima Maxima Minima

1 0 0.3 0 222 2 1.45 0.8 107 59

3 1.95 1.7 143 1254 2.45 2.1 180 1545 3.25 3.06 239 2256 4.30 3.53 316 2607 4.90 4.63 360 340

polar plot (Figure 9) ofthese points is shown at the detector radius super-imposed on a sketch of the outlines of the density variations observed from !hephotograph of Figure 8.

The calculated location of the holes in the plexiglass agrees with theiractual location to within less than 1 percent. The visually observed variationsin the RTV bonding material seen in the photograph (Figure 8) do not exactly

__ correspond with the location of the maxima and minima plotted in Figure 9.This might be attributed to the lack of uniformity of the bonding defect.

3. Motor Case Data

The following methods were used to establish the feasibility andtechnical problem areas of an IR scanning NDT applicable to detection of rocket

motor defects.

A motor case of Y1/-inch steel, 3-inch inside diameter by 10-inch lengthwas insulated with a Y1 8-lnch sheet of phenolic asbestos. A small amount ofgrease was applied to a localized area of the case to create an unbonded region

FA during liner attachment to the motor case. The insulation was cut to form atriangular crack 1/10 inch at the widest point. The apex decreased to a hairlineapproximately 2 /2 inches from the motor edge and extended the length of thecase (Figure 10). With these "built-in defects the output signals of the IRsensor could be more easily interpreted.

10- ----• I, - I- -

•@ ac '-2

A helical scanning technique Was w-led in which the motor was rotated ona lathe spindle while the sensor, mounted on the carriage, traversed the caseparallel to its axis.

Various methods were investigated to raise the surface under inspectionto a measurable temperature. These methods involved the use of radiant andconvective heating of both large and small areas from either inside or outsidethe motor wall (9]. Spot heating by tungsten lamps resulted in insufficientenergy transfer for the required temperature differential. Radiant heating ofthe interior of the case by an axially mounted heating element rapidly increasedthe thermistor detector temperature above its optimum operational range. Thisproblem was also experienced during convection heating by hot air. To main-tain a small resolution element without resorting to lenses, it was necessary tolocate the sensor within a minimum distance of the motor wall of about0. 050 inch. This fact appeared to eliminate all methods involving total heatingof the motor case. The most successful approach involved the use of an auto-mob~le lighter mounted inside the motor wall with the sensor outside. The

lighter provided sufficient radiant energy to produce sensor signals indicativeof the radial rate of heat transfer through the motor wall. With the~sensjor andlighter mounted stationary with respect to each other on the carriage, and onopposite sides of the motor wall, the entire surface could be scanned. Anadvantage of this heating technique is that the elliptical shape of the motor casedoes not appreciably affect the signal level. Signal variations due to heating bythe inverse square effect are effectively compensated by maintaining a fixedradial distance between the source and sensor, regardless of the wal11 position.

It was found that optimum positioning at the lowest rotation rate of the lathe waswhen the sensor was displaced 90 degrees with respect to the lighter.

First attempts to identify insulation defect- from the recorded signalswere unsuccessful. This fact was later attributed to emissivity variationswhich appeared to predominate over the surface temperature variations. In aneffort to eliminate emissivity variations, the motor case was sprayed with auniform coating of flat black paint and the experiment attempted once more.This time a clear correlation could be drawn between the record and the posi-tions of the defective areas. Figure 11 illustrates successive helical scans ofthe motor surface. In reference to Figure 10, which is a scale layout of themotor, one may see the beginning point of each scan, located about 5Y2 inchesfrom the right end.

With the lateral scan rate of 0.11 inch per second and a motor rotationrate of 0.4 revolution per second, the total scan time for the inspected areawasapproximately 50 seconds. The exact size of the unbonded area was unknown,and it is therefore difficult to establish with certainty that the scans reflect itsexistence; however, irregularities measured while the sensor was in the area,

4K °

of the unbond seem to indicate its detection. The regularity of the recordedpulses in the area of the crack leaves no doubts whatever concerning its detection.The intensity and duration of the pulse in the widening area of the crack areclearly observed. Extrapolation of the pulse interval to the beginning of the tracealso reveals a slight indication of the hairline crack along the full length of thecase. From these considerations and results found in the current literature [4]it is possible to conclude that IR inspection of motor cases is definitely feasible.

NII

I

12

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THIERHISTOR SIAScaiquif

JJAM1PLIFIER AMIPLIFIER

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~ IFIGURE 4. WIRING DIAGRAM OF TEMPERATURE CONTROLLER

83

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FIGUR 8.POTGtHOFISUAEDDS

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M• INIMA

FIGURE 9. POLAR PLOT OF DETECTOR RESPONSE

17

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X 94.

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Section IV. CONCLUSIONS AND FUTURE PLANS

From this study it has been determined that: 1) It is feasible to use IRradiation as a means of non-destructive testing of rocket motor case insulation;2)- The non-cryr. oenic thermistor bolometer has sufficient sensitivity to detect-insulation non-uniformities; 3) A closed loop control system is useful tostabilize the detectors' thermal operating point, permitting dc coupling of thedetector output.

Future work will involve optimizing individual component performancein order to increase the overall system response. Germanium immersedthermistor detectors with appropriate preamplifiers will be mounted in atthermoelectrically stabilized assembly operated near room temperature. Arecording technique will be selected to ease data interpretation. An example

-wotild-be to intensity-modulate a storage oscilloscope in order to produce athermal image similar to a photograph of the mouor case being inspected. Thesystem bandwidth must be sufficient to allow detection of predicted defects atthe selected scanning speed.

The system obtained as a result of the above procedure will be used to-examine a number of motor cases with known insulation defects. These motorcases will then be static fired in order to correlate the inspection results withactual motor case failures such as case burnthrough. Instrumentation to detectlocalized motor case heating while static firing will be evaluated, e. g., theBarnes IM camera, If a unit becomes available.

20

Si I-• _ -_- -- - --L• -- =: -- •• ... .. . .. --

REFERENCES

1. U. S. Army Missile Command, Redstone Arsenal, Alabama, RRocket Motor Case Insulation Bond Investigation by Otis ). Hartley,November 1,P68, Report No. RT-TM-69-2.

2. Lion, K. S., I,,strumentation in Scientific Research, McGraw-Hill BookCompany, New York, 1959, p. 166.

3. Kutzcher, E. W., Zimmerman, K. H., and Botkin, J. L., "Thei-mal'and Infrared Methods for Nondestructive Testing-of AdheiiVe Bonded'Structures," Transactions of Infrared and Thermal Sessions of_American Society for Non-Desctructive Testing, hic., October 1967,p. 52.

4. Vogel, P. E., "Evaluation of Bonds in Armour Plate and-Othe iMaterials-Using Infrared Non-Desctructive Testing Techniques," Aiplied&OpticD,Vol. 7, No. 9, September 1968, pp. 1739-1742.

5. Barnes Engineering Company, Bulletin No. 2-100, Thermistor Infrared-Detectors.

6. Gheorghiu, Paul, "Contribution to the Fast Warm-Up and Close :Tempera-ture Control Oven Thoory," IEEE Transactions on IndustrialiElectroiiicsand Control Instrumentation, Vol. IECI-13, April 1966, p. 86.. ..

7. Caldwell, W. I., Coon, G. A., and Zoss, L. M., Frequency ReSponsefor Process Control, McGraw-Hill Book Company, New York, 1959,--p. 32.

8. Melsa, J. L., and Schultz, D. G., Linear Control Systems, McGraw-Hill Book Company, New York, 1969, p. 378.

9. Maley, D. R., "Two Thermal Nondestructive Testing. Techniques,"Transactions of the Infrared Sessions, February 1965, Paper No. 4.

10. Forsythe, W. E., Measurement of Radiant Energy, McGraw-Hill BookCompany, New York, 1937, p. 380

21

UNCLASSIFIEDSe~curity Classification

DOCUMENT CONTROL DATA. R & D(Security classification of title. bod of *"fete$c and Indexing ennotation stuat be entered when the overall repr rIe lcelasifed)

1. ORIGINATING ACTIVITY (Corpoedge A~dir) 20. REPORT SECURITY CLASSIFICATIONArmy Propulsion Laboratory and Center UcasfeResearch and Engineering Directorate (Provisional) UcasfeU. &.t Army Missile Command bGOURet Anrsenal, Alabama 35809 N/A

3.REPORT TITLE

FEASIBILITY OF ROCKET MOTOR INSULATIONINSPECTION USING INFRARED RADIATION

4. DESCRIPTIVE NOTES (Type otfrpair and Inetualva datea)

None0. AUTHOR(S) (Piet naess. NJ=iddnitial, faet name)

D. R. DreitzlerL. B. Thorn

O.REPORT DATE 7e. TOTAL NO. OF PAGES 6b NO. or REPS

26 November 1969 27 10S&. CONTRACT OR GRANT NO. S&. ORIGINATOR's REPORT NUMSER(S)

b. PROJECT NO. (D)l220~5RK-TR-69- 15

e.AMC Management Structure Code No. Ob. OTHER NEPORT NO(S) (Any? 0the. .,afbeto Meatma" be *@signedthle report)

AD_______________10. DWSTRIOUTION STATEMENT

This document is iaubject to special export controls and each transmittal to foreign governmentsor foreign nationals may be made only with prior approval of this Command, ATTN:AMSMI-RK. _ _ _ _ _ _ _ _ _ _ _

1t). SUPPLEMENTARY NOTES 1I2. SPONSORING MILITARY ACTIVITY

None Same as No. 1

It. ASSTRACT

SInsulated, thin-wall motor cases have as a potential failure mode the burnthroughof MIe motor case wall resulting from a defective liner. The objective of thisinvestigation was to determine the feasibility of the use of infrared radiation as a meansof noni-destructive examination of an insulated motor case in order to detect a potentiallydefective liner. A relatively inexpensive infrared inspection system was designed andassembled which demonstrated that it is possible to detect cracks and density variationsin the Insulation of rocket motor cases. (

MKPLA4ES DO PORM 1478. 1 JAN 04. WHICDD NovSol473 0098TaI PAM" AUse. UNCLASSIFIED5.cMity classmlncue 23

UNCLASSIFIEDSecurity ClauuifieSTlO.

14. LINK A LINK 11 LINK CKIEV WORDS - --

"01.4 WT ROLS WY ROLZ WT

FInsulatecd motor case 1Non-destructive examinationu4Infrared radiation

i6'

UNCLASSIFIED24 Utewity c1assitrceioe

'77